Quick operating device for a valve

ABSTRACT

A mechanism utilizing a pair of cooperatively associated hydraulic cylinders and springs for absorbing and storing the energy produced by slowing down a large on-off type valve having a fast closing action as the valve approaches its closed position and releasing the energy to open the valve quickly.

United States Patent [191 Lewis [11] 3,746,299 [451 July 17,1973

[ QUICK OPERATING DEVICE FOR A VALVE [75] Inventor: Ivor J. Lewis,Marple Woods, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

.[22] Filed: July 19, 1971 [21] Appl. No.: 163,582

52 user. ..2s1/2s,251/73 51 Int. Cl. ..Fl6k31/l43 [58] FieldofS earch251/73, 27,136,

[56] References Cited UNITED STATES PATENTS 3,591,127 7/1971 Luger251/73 X New 7 Zenor 251/136 X 2,910,266 Condello ct al. 251/25 PrimaryExaminer-Arnold Rosenthal Attorney-A. T. Stratton et al.

57 ABSTRACT A mechanism utilizing a pair of cooperatively associ- 8Claims, 2 Drawing Figures weep 1 QUICK OPERATING DEVICE FOR A VALVEBACKGROUND OF THE INVENTION This invention pertains to a quick operatingvalve for a steam turbine and more particularly to a large quickoperating valve in which energy absorbed from the valve as it approachesits closed position is stored and subsequently released to open thevalve rapidly.

To keep pace with the high rate of growth of power consumption, powercompanies have been installing larger and larger turbogenerator unitsoperating at high pressures and temperatures, which make reheating thesteam after it has been partially expanded in the high pressure portionof the turbine economical. Utilizing reheat cycles necessitatesinstalling stop and interceptor valves in the piping between thereheater and the turbine as the reheater contains a large quantity ofsteam, which if allowed to expand through the turbine after the turbineloses its load, could cause internal damage to the turbine. Theintercept valve is controlled by a controller responsive to theelectrical load on the generator and the pressure in the reheat pipingso that the intercept valve anticipate losses of electrical load tobegin shutting down the turbine at the first indication of loss ofelectrical load. Many of the disturbances, which cause a circuit breakerto open and produce an indication of loss of load on the turbine, willbe transient and clear themselves. Thus, it is common practice toprovide circuit breakers, which will automatically reclose'one or moretimes before finally locking themselves out. Quick operating valves,thus serve two functions, the first being to cut off the steam to thelow pressure portion of the turbine as fast as possible by initiatingclosing of the intercept valve upon the first indication of possibleloss of load, and the second being to provide an interruption in thesteam flow to balance the transient loss of load on the generator. Amomentary loss of load on the generator causes the turbine to speed upwhich is compensated for by a momentary closing of the intercept valveproviding a coarse speed control, thus reducing changes necessary in themain steam control system to keep the speed of the turbine constantirrespective of the rapid variations in load associated with opening andreclosing of the circuit breakers during transient load losses.

SUMMARY OF THE INVENTION In general, a device for operating an on-offvalve, when made in accordance with this invention, comprises ahydraulic mechanism for opening the valve at a relatively slow rate, acombined hydraulic and mechanical mechanism for closing the valverapidly, a combined hydraulic and mechanical mechanism for absorbing andstoring the energy associated with slowing the valve down as itapproaches its closed position, and a device for releasing the storedenergy to accelerate the valve in opening direction to open the valvequickly.

BRIEF DESCRlPTlON OF THE DRAWINGS The objects and advantages of thisinvention will become more apparent from reading the following detaileddescription in connection with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a turbogenerator unit having anintercept valve disposed therein; and

FIG. 2 is a schematic diagram of an operator for an intercept valve madein accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings indetail, FIG. 1 shows a turbogenerator unit comprising a high pressuretur- The intercept valve 11 is controlled by a signal produced by atransducer 19 responsive to the pressure in the piping 13 between thereheater and the intermediate pressure turbine 3 and a signalproportional to the load on the generator 15. These signals areproportional to each other so that when the signals become unbalanced asignal from a controller 20 is sent to a device 21 operating theintercept valve 11 to cause it to close rapidly. The signal to close thevalve could be caused by any unbalance due to any momentary trouble in atransmission line 23, such a momentary fault due to lightning or othercauses, which would open a circuit breaker (not shown). When the circuitbreaker opens the load is reduced causing an unbalance between thereheat pressure and the load resulting in the signal being sent from thecontroller 20 to the operating device 21 of the intercept valve 11causing the valve to close rapidly. After a time delay the operatingdevice 21 tries to reset itself, if the circuit breaker remains open theunbalance remains and the intercept valve does not reset, but remainsclosed. On the other hand, if the circuit breaker recloses, due to thefault on the transmission line 23 having cleared itself, the breakerremains closed and the controller resets itself sending a signal to thedevice 21 to open the valve 11 rapidly. The reduction in the amount ofpower produced by the generator when the breaker is open approaches theamount of power not produced by the turbine, when the intercept valve isclosed, reducing the number of changes that would normally be requiredin the steam flow control system to slow the turbine down when thebreaker opens and then to speed the turbine up when the breaker closesagain picking up the load. While the load loss due to the circuitbreaker opening does not match the reduction in load associated withclosing the intercept valve, they are sufficiently closely related toprevent overspeeding of the turbine to such a degree that it will tripthe overspeed trip and also reduce the hunting in the'control system.

As shown in FIG. 2, the intercept valve 11 is a butterfly valve having acrank arm 25 disposed normal to a disc 27 and the disc 27 is mounted sothat it rotates from the valves fully open position to the valves closedposition. The device 21 for operating the valve 11 comprises a firstsingle acting hydraulic cylinder 29 having a first movable abutment orpiston 31 disposed therein to form a first chamber 33. A supply conduit35, having an orifice 37 disposed therein, supplies pressurized fluid toone side of the piston 31 to bias a piston rod 40 in one direction toopen the valve 11 at a normal rate. The piston rod 40 is pivotallyconnected at its free end to one end of a connecting rod 39. The otherend of the connecting rod 39 is pivotally connected to the end of thecrank arm 25. A first spring 41 reacts against a disc 43 fastened to thepiston rod 40 to bias the valve 11 in closing direction. The spring 41has a sufficiently large modulus or rate to close the valve rapidly,when the pressurized fluid biasing the valve in opening direction isdumped from the chamber 33. A drain conduit 45 is connected to the firstchamber 33 and has a quick opening valve 47 disposed therein to dump thepressurized fluid from the chamber 33 to allow the valve 11 to closequickly.

The device 21 also comprises a second hydraulic cylinder 49 having asecond movable abutment or free piston 51 disposed therein to form asecond chamber 53, and a second spring 55. The second spring 55 isenclosed in a housing 57 and reacts against the housing and a disc 59connected to one end of a rod 61 slidably disposed with respect to thehousing 57. The piston rod 40 and the rod 61 are connected by a balancearm or lever 63 pivotally mounted adjacent its center. One end of thebalance arm 63 is disposed to slidably engage a disc 65 fastened to thepiston rod 40, when the valve 11 approaches its closed position, and theother end is pivotally connected to one end of the rod 61 so that as thevalve 11 approaches its closed position the balance arm 63 pivots aboutits center mount 67 to stress or compress the second spring 55 absorbingenergy from the valve 11 as it approaches its closed position. The valve11 may be several feet in diameter and weigh several tons and thevelocities associated wijh quick closing are high, so that the inertiaof the valve 11 or available energy to compress the spring 55 is verylarge. The time interval during which the second spring 55 is compressedis short, so that the disc 59 leaves the free piston 51 during that timeinterval. The free piston 51 is biased toward the disc 59 by pressurizedfluid supplied through a supply conduit 69 having a check valve 71disposed therein. The area of the piston and the pressure of thepressurized fluid are not sufficiently large in combination, to compressthe second spring, but the pressurized fluid moves the free pistontoward the disc 59 filling the chamber 53 with pressurized fluid. Thefirst and second chambers 33 and 53, respectively, are placed incommunication by a connecting duct 73 having a fast operating valve 75and a check valve 77 disposed therein.

The valve 75 is operable from a signal from the controller 20 indicatingthat the valve 11 should open rapidly to allow pressurized fluid fromthe second chamber 53 to flow to the first chamber 33 and cooperate withthe second spring 55, which acts through the balance arm 63, toaccelerate the valve in opening direction. The check valve 77 ensuresthat the fluid flows from chamber 53 to chamber 33 preventing flow inthe reverse direction if the pressure in chamber 33 is momentarilyhigher'than the pressure in chamber 53, during the initiation of thequick opening portion of the cycle. The second spring 55and the secondchamber 53 cooperate to supply the force necessary to accelerate thevalve 11 in opening direction and to supply the necessary quantity offluid to the first chamber 33 to allow the valve 11 to be openedrapidly. Thus, the first and second cylinders 29 and 49 arecooperatively associated to absorb energy from the valve 11 as itapproaches its closed position and to store this energy in the secondcylinder 49 and second spring 55 and to release the stored energy toopen the valve rapidly upon receiving the proper signal from thecontroller 20.

What is claimed is:

1. A quick operating device for a valve, said device comprising a firstchamber and a first movable abutment disposed therein, said firstmovable abutment being cooperatively associated with said valve to openand close said valve, a first spring cooperatively associated with saidfirst movable abutment to bias the valve in closing direction,

a second chamber and a second movable abutment disposed therein,

a second spring cooperatively associated with said first movableabutment to absorb energy from the valve as the valve approaches itsclosed position, means for supplying a charge of pressurized fluid tosaid second chamber when said second spring is compressed,

a conduit between said first and second chamber, and

means for controlling the flow in said conduit so that pressurized fluidfrom said second chamber may be supplied to said first chamber to opensaid valve quickly.

2. A device as set forth in claim 1 and further comprising means forsupplying pressurized fluid to said first chamber to open said valve ata normal rate.

3. A device as set forth in claim 1 and further comprising means fordumping the fluid in said first chamber to close the valve quickly.

4. A device as set forth in claim 1, wherein the second chamber is ahydraulic cylinder and the second movable abutment is a floating pistonmovable in one direction by a pressurized fluid when the second springis compressed and movable in the other direction by the second spring tosupply pressurized fluid to said first chamber at a high rate to closethe valve quickly.

5. A device as set forth in claim 1, wherein the means for supplyingpressurized fluid to the second chamber is the supply conduit forpressurized fluid with a check valve disposed therein.

6. A device as set forth in claim 1, wherein said second spring iscooperatively associated with said second movable abutment to providethe sufficient charge in pressurized fluid to produce rapid accelerationof said valve in opening direction when the flow control means is open.

7. A device as set forth in claim 1, wherein the second spring and saidcharge of pressurized fluid cooper ate to accelerate the valve inopening direction when the control means is open.

8. A device as set forth in claim 1 wherein the modulus of the firstspring is greater than the modulus of the second spring.

a: w: a -a 1|:

1. A quick operating device for a valve, said device comprising a firstchamber and a first movable abutment disposed therein, said firstmovable abutment being cooperatively associated with said valve to openand close said valve, a first spring cooperatively associated with saidfirst movable abutment to bias the valve in closing direction, a secondchamber and a second movable abutment disposed therein, a second springcooperatively associated with said first movable abutment to absorbenergy from the valve as the valve approaches its closed position, meansfor supplying a charge of pressurized fluid to said second chamber whensaid second spring is compressed, a conduit between said first andsecond chamber, and means for controlling the flow in said conduit sothat pressurized fluid from said second chamber maY be supplied to saidfirst chamber to open said valve quickly.
 2. A device as set forth inclaim 1 and further comprising means for supplying pressurized fluid tosaid first chamber to open said valve at a normal rate.
 3. A device asset forth in claim 1 and further comprising means for dumping the fluidin said first chamber to close the valve quickly.
 4. A device as setforth in claim 1, wherein the second chamber is a hydraulic cylinder andthe second movable abutment is a floating piston movable in onedirection by a pressurized fluid when the second spring is compressedand movable in the other direction by the second spring to supplypressurized fluid to said first chamber at a high rate to close thevalve quickly.
 5. A device as set forth in claim 1, wherein the meansfor supplying pressurized fluid to the second chamber is the supplyconduit for pressurized fluid with a check valve disposed therein.
 6. Adevice as set forth in claim 1, wherein said second spring iscooperatively associated with said second movable abutment to providethe sufficient charge in pressurized fluid to produce rapid accelerationof said valve in opening direction when the flow control means is open.7. A device as set forth in claim 1, wherein the second spring and saidcharge of pressurized fluid cooperate to accelerate the valve in openingdirection when the control means is open.
 8. A device as set forth inclaim 1 wherein the modulus of the first spring is greater than themodulus of the second spring.